1. Field of the Invention
The present invention pertains to medical instruments and, more particularly, to a valve assembly for providing a variable size passage in an endoscopic portal to prevent fluid through the portal while allowing implements of various sizes to be selectively introduced through the valve.
2. Description of the Prior Art
Medical procedures involving the placement of an endoscopic portal, such as a sleeve or cannula, through an anatomical cavity wall to provide a passage for insertion of medical instruments frequently required that the passage be sealed to prevent the flow of fluids through the endoscopic portal. For example, many medical procedures gain access to an anatomical cavity by utilizing a penetrating member, such as a trocar, obturator or needle, having a sharp penetrating tip for puncturing the cavity wall to establish communication with the interior of the anatomical cavity. A sleeve or cannula is then left in situ for utilization as a portal to introduce medical instruments into the anatomical cavity. Because it is necessary to prevent fluid flow to and from the site within the anatomical cavity, the portal must be sealed prior to and subsequent to the introduction of any instruments and while such instruments are in place. Furthermore, fluids, such as gaseous phase carbon dioxide or nitrous oxide, may be introduced into the anatomical cavity for insufflation as part of the procedure, and the escape of the gas must be prevented during penetration and during the endoscopic procedure. Typically, medical instruments are inserted into the portal via a valve that has a single, particular size passage dependent upon the penetrating member. However, additional instruments to be introduced into the anatomical cavity through the passage may be of diverse types and sizes and it will be appreciated that fluid can escape past smaller instruments.
A penetrating member is usually received within a portal sleeve that passes through the wall of an anatomical cavity with the penetrating member and remains in place to establish communication with the interior of the cavity after the penetrating member has been removed from the sleeve. The sleeve typically has a proximal end secured in a housing provided with a valve that allows the penetrating member to be inserted into the sleeve. The valve prevents the flow of fluids to and from the anatomical cavity and closes when the penetrating member is removed from the sleeve. The size of the penetrating member utilized varies depending upon the procedure and the type of anatomical cavity to be penetrated. Once the penetrating member has been removed from the sleeve, a great variety of instruments of various sizes and diameters are introduced into the anatomical cavity via the portal dependent upon the procedure to be performed.
Prior art endoscopic portals utilize a valve, such as a flapper or gate valve, that is normally biased to a closed position but in an open position has a passage or lumen therethrough of only a single size. Accordingly, such endoscopic portals suffer from the disadvantages of allowing the passage or leakage of fluids when surgical instruments smaller than the single passage are introduced therethrough or of limiting the implements to be used in a procedure to a single size. Additionally, such endoscopic portals can be effectively used with only a single size penetrating member.